Plot holes question?

I just got to the point in HoFaS where Pollux says they fixed the harpy. I literally don’t understand why SJM is doing this back from the dead crap. Harpy was basically decapitated and a sword through her spine. Meanwhile they never tried saving saving Sandriel. Since when can they fix people to that extent ?

Another plot hole but someone confirm- I’m pretty positive Azriel can Winnow. They are in the cave tunnels acting like only Bryce can when they get before the door that takes them to the prison. It’s cassian that can’t. I know this is true because in ACOMAF feyre says she will go with azriel when they go to see her sisters for the first time. But he suddenly has lost that powder in HoFaS?

Lastly I think the torture in the dungeon and extent of growing back limbs and stuff is crazy. Other times they are faced with death and people are actually afraid they are going to die. Meanwhile hunt, ruhn and baxian are getting intestines ripped out, things cut off and things that definitely give vanir infections and they are still alive. Serious plot armor. Don’t think this level of torture is necessary either.